With continuous development of automobile industry, steering systems of automobiles have obtained rapid progresses, and an electric power steering system is the development direction of automobile steering systems. The steering power of the system is directly provided by a steering motor some components required by traditional hydraulic power steering systems are then omitted, and hence not only is energy saved but also the environment is protected. Furthermore, the system further has features that it is easy to be adjusted and flexible to be assembled and the steering power can be provided under various circumstances.
When a driver operates a steering wheel to veer, a torque sensor detects the veer of the steering wheel and the extent of the torque, and transmits a voltage signal to an electronic control unit. The electronic control unit sends an instruction to a steering motor controller according to the torque voltage signal, the steering direction, and the automobile speed signal detected by the torque sensor, and makes the steering motor output a steering power torque with corresponding magnitude and direction, thereby producing auxiliary power. When the automobile does not veer, the electronic control unit will not send any instruction to the motor controller, and the motor does not work.
When a vehicle runs on a road with bad road conditions, the whole vehicle shakes with the steering motor continuously. In order to overcome the bad influence that the bad road conditions cause shocks of the steering motor, a damping system is arranged inside the steering motor. A traditional damping system generally utilizes a carbon brush and a collector ring; when the steering motor suffers shocks, the damping system begins to work and constantly buffers the shocks, which makes the carbon brush and the collector ring be rubbed continuously, hence the carbon brush and the collector ring may be worn and damaged due to friction. Furthermore, the carbon brush and the collector ring are sensitive to temperature, and are prone to damage because of temperature changes, such that the stability and service life of the steering motor are seriously affected.
In addition, existing steering motors are generally provided with a variety of oil passages, such as oil passages for shock absorption oil supply, oil passages for braking oil supply, oil passages for hoist oil supply, etc; however, these oil passages are all designed independently and assembled separately, such that each of the oil passages are isolated from each other. Thus, the oil passages occupy too much space in the steering motor, such that the structure of the steering motor is complex, which not only wastes resources but also increases manufacturing cost.